Adaptive pulse width control power conversation method and device thereof

An adaptive pulse width control power conversion device, through which an input voltage source is subjected to conversion and supplied to a load, the device comprising:

• a pulse width adjustable pulse frequency modulation (PFM) control circuit, which generates a series of PFM control signals;
• a pulse width modulation (PWM) control circuit, which generates a series of PWM control signals;
• a PWM/PFM switching unit, which connects between the pulse width adjustable PFM control circuit and the PWM control circuit;
• a switching circuit, which is connected to the input voltage source and the pulse width adjustable PFM control circuit, the switching circuit being controlled by a pulse width control signal that is an output of one of the PFM control signal and the PWM control signal, a filter circuit supplying an output voltage to the load;
• and
• a load status detection circuit, which detects a feedback status signal of the load and applies the feedback status signal to the pulse width adjustable PFM control circuit and the PWM control circuit;
• wherein when the power conversion device is to be switched from a PWM mode to a PFM mode, the pulse width adjustable PFM control circuit generates a series of PFM control signals according to a predetermined pulse width and pulse width of the PFM control signal is sequentially adjusted from a low value to a high value according to a predetermined pulse width increment until an optimum pulse width is determined in accordance with the feedback status signal, and thereafter, the output voltage is supplied to the load in the PFM mode according to the pulse width adjusted optimum pulse width;
• wherein the pulse width adjustable PFM control circuit comprises:
• a control unit;
• a memory unit, which is connected to the control unit, the memory storing the pulse width increment;
• a pulse generator, which is connected to the control unit and is controlled by the control unit to generate the PFM control signal;
• and
• a pulse width comparator, which is connected to the pulse generator to compare and identify a greater one of pulse widths of the PFM control signal and the PWM control signal as an output of the pulse control signal.